1. Field of the Invention
This invention relates to N.sup.4 -alkoxycarbonylarabinofuranosylcytosine which is a novel compound exhibiting excellent antitumor effect.
2. Description of the Prior Art
Arabinofuranosylcytosine represented by the formula: ##STR2## is useful and highly evaluated as an antitumor agent widely in clinical applications. But its effect can be exhibited only by non-oral adminstration and the compound suffers from the disadvantage of being ineffective by oral adminstration. This is considered to be due to the fact that said compound is changed to arabinofuranosyluracil having no antitumor effect by the action of deaminase existing in human bodies when it is absorbed through intestines.
The present inventors have made extensive studies to develop a derivative which will not lose its effect even by oral administration by overcoming the disadvantage of arabinofuranosylcytosine represented by the formula (I). Consequently, they have found that a novel compound having an amino group at the 4-position protected with an alkoxycarbonyl group has an excellent effect by oral administration to accomplish the present invention.
As a N.sup.4 -alkoxycarbonyl derivative of arabinofuranosylcytosine known in the art, there is only tri-haloethoxycarbonyl derivative as diclosed in J. Medicinal Chemistry, Vol. 14, No. 12, 1159-1162(1971). This is, however, a synthetic intermediate and there is no examination about its antitumor effect. The present compound is for the first time provided as a N.sup.4 -alkoxycarbonyl derivative for the purpose of oral administration.